In praise of ... Perseids meteors

Warm evenings and dark skies, thanks to a new moon, should make the week ahead an excellent one for stargazing - and it comes as one of the most impressive annual meteor showers reaches its peak. Not really shooting stars, although they are often called that, meteors are a transient and energetic part of the night sky, a brief flash of light like a gentle natural firework. They are the visible evidence of cosmic dust as it brushes the earth, leaving a trail of light when the specks ram into the atmosphere. This week, as the earth passes through the debris of Swift-Tuttle's comet, the Perseids meteor shower should be visible to anyone who can escape the glare of city lights. It has already begun, and reaches its peak tomorrow night. Amateur observers will be lucky to spot the beautiful early evening "earthgrazers", which skim across the top of the atmosphere; the show should increase in intensity in the hours before dawn. The Perseids are the most famous and observed of meteors. Chinese astronomers recorded them almost 1,000 years ago: in 36AD it is said "more than 100 meteors flew thither in the morning". They were noted again on 10 August 258, just before the execution of St Lawrence in Rome, and became known as the "tears of St Lawrence". Ever since, they have been associated with his saint's day. The Perseids should be visible, if the skies are clear, in the sky to the north-east, from 11pm tomorrow night until dawn: a perfect excuse for a nocturnal excursion.